For Release January 28, 2003

Cold Is Good

AGRI-VIEWS
by Chuck Otte, Geary County Extension Agent

After an almost two year absence we once again saw temperatures in the subzero range. While a lot of folks were complaining about this weather, I was rejoicing! You see, not only do we periodically need cold cold temperatures, we also need those yo-yo temperatures that we both hate and love. While all these weather extremes may be tough on us, itís the very sort of weather that has shaped the Great Plains for the past few millennium. Now while this weather may not cure all of our ills, itís going to help in many ways.

Have you ever thought about what it would be like if we didnít have cold weather. I mean really cold subfreezing, subzero temperatures? I got to spend a month in a country where this never happens. I think weíre all familiar with a plant known as milkweed. A deep rooted perennial that is known for being the food of Monarch butterfly caterpillars, milk sap and seed pods that explode in a wind blown fluff, milkweeds are around every year and freeze back to the ground every fall. Did you ever think what they would look like if it never froze? There is a close cousin of our milkweed that grows in West Africa. It doesnít freeze in West Africa. The milkweed plants there would grow into woody shrubs over ten feet high. I saw milkweeds with woody trunks eight inches in diameter.

Having a real winter not keeps certain plants in control. Because of freezing weather, the vine kudzu isnít a problem, it isnít even in many local residents vocabulary. Have you ever considered what poison ivy or field bindweed would be like if it never froze? Many of our plants actually need cold weather to bloom or bear fruit. Winter wheat is most notable. Peaches need a certain amount of "chilling" before they will bloom. Many of our spring flowering bulbs wonít bloom in far southern climates simply because it doesnít have a cold season to trigger the blooming process. We may curse that cold weather, but it is a real benefit to many of our plants!

What about insects? Would it make a difference if it never froze? Sure it would. By having several months during the year with lots of freezing temperature we give everyone a chance to have a break from insects. Sure, they go into hibernation and come back out next spring, but that break is very critical. The winter helps break insect borne disease cycles and keeps insect populations in check. In Africa alone, over one million people a year die of Malaria. In the United States, we average less than twenty deaths from malaria annually. I think Iíll take the cold winter weather.

Does it help reduce the number of over-wintering insects by getting cold and staying cold? Yes it does, but not as much as one might think. We all know that there are more insects around in the early spring following a very mild winter than a very hard winter. But what is hardest on over-wintering insects is a lot of variability. Every time it warms up, the hibernating insect starts to wake up and get active. This uses up food reserves. Then every time it gets cold again, they go back into hibernation, without replenishing those spent food reserves. The more times this cycle is repeated, the more insects die, quite literally from starvation. So a winter with a lot of up and down temperatures does more to reduce insect numbers than getting cold and staying cold.

It wasnít any fun shoveling snow at five degrees. My fingers got cold, my toes got cold, my face was cold. But it didnít take long to get the job done and I was back inside. And the whole time I was thinking about how much good that cold weather was doing for our plants, our insects and all the crops we try to grow. Sure itís a nuisance, but itís a necessary nuisance!

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